Systems and methods for in-situ fabric link optimization in a modular information handling system chassis

ABSTRACT

In accordance with embodiments of the present disclosure, a method may include, during boot of a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources, pausing execution of a basic input/output system. The method may also include communicating a first indicator, wherein the first indicator causes a chassis management controller of the chassis to perform link optimization operations of a communication link between the modular information handling system and a modular information handling resource. The method may further include, in response to communication by the chassis management controller of a second indicator, the second indicator indicating completion of link optimization operations by the chassis management controller, unpausing execution of the basic input/output system.

TECHNICAL FIELD

The present disclosure relates in general to information handling systems, and more particularly to fabric link optimization in a modular information handling system chassis.

BACKGROUND

As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.

Existing server architectures either provide a single monolithic server capable of running one operating system (or a single hypervisor running multiple virtualized operating systems) and input/output (“I/O”) resources at a time, or bulky blade server chassis providing multiple servers and I/O control modules in a single chassis. A system chassis with multiple information handling systems with various peripheral and I/O capabilities common to the chassis as a whole may provide advantages, as it allows a blade server chassis in a small form factor, thereby providing a blade server chassis with a size comparable to the size of a monolithic server. Implementation of a system chassis with multiple information handling systems with various peripheral and I/O capabilities common to the chassis as a whole presents numerous challenges. One of such challenges is optimizing communications links between information handling systems and endpoints within a system chassis.

SUMMARY

In accordance with the teachings of the present disclosure, the disadvantages and problems associated with multipath I/O configuration have been reduced or eliminated.

In accordance with embodiments of the present disclosure, an article of manufacture comprising may include a non-transitory computer readable medium and computer-executable instructions carried on the computer readable medium. The instructions may be readable by a processor, and, when read and executed, may cause the processor to, during boot of a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources pause execution of a basic input/output system. The instructions may also cause the processor to communicate a first indicator, wherein the first indicator causes a chassis management controller of the chassis to perform link optimization operations of a communication link between the modular information handling system and a modular information handling resource. The instructions may further cause the processor to, in response to communication by the chassis management controller of a second indicator, the second indicator indicating completion of link optimization operations by the chassis management controller, unpause execution of the basic input/output system.

In accordance with these and other embodiments of the present disclosure, a method may include, during boot of a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources, pausing execution of a basic input/output system. The method may also include communicating a first indicator, wherein the first indicator causes a chassis management controller of the chassis to perform link optimization operations of a communication link between the modular information handling system and a modular information handling resource. The method may further include, in response to communication by the chassis management controller of a second indicator, the second indicator indicating completion of link optimization operations by the chassis management controller, unpausing execution of the basic input/output system.

In accordance with these and other embodiments of the present disclosure, an article of manufacture comprising may include a non-transitory computer readable medium and computer-executable instructions carried on the computer readable medium. The instructions may be readable by a processor, and, when read and executed, may cause the processor to, perform link optimization operations in a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources. The link optimization operations may include: (i) determining if a modular information handling resource disposed in the chassis and communicatively coupled to a modular information handling system disposed in the chassis is identified in a whitelist; (ii) if the modular information handling resource is identified in the whitelist, retrieving typical operating parameters associated with the information handling resource; (iii) if the modular information handling resource is identified in the whitelist, retrieving target operating parameters associated with the information handling resource; (iv) determining if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system satisfy the typical operating parameters or the target operating parameters; and (v) performing a remedial action if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system do not satisfy the typical operating parameters or the target operating parameters.

In accordance with these and other embodiments of the present disclosure, a method may include performing link optimization operations in a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources. The link optimization operations may include: (i) determining if a modular information handling resource disposed in the chassis and communicatively coupled to a modular information handling system disposed in the chassis is identified in a whitelist; (ii) if the modular information handling resource is identified in the whitelist, retrieving typical operating parameters associated with the information handling resource; (iii) if the modular information handling resource is identified in the whitelist, retrieving target operating parameters associated with the information handling resource; (iv) determining if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system satisfy the typical operating parameters or the target operating parameters; and (v) performing a remedial action if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system do not satisfy the typical operating parameters or the target operating parameters.

Technical advantages of the present disclosure may be readily apparent to one skilled in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1 illustrates a block diagram of an example system chassis with multiple information handling systems and with various peripheral and I/O capabilities common to the chassis as a whole, in accordance with embodiments of the present disclosure;

FIG. 2 illustrates a more detailed block diagram of an example system configured for switches and devices in a multi-root I/O virtualization environment for multiple information handling systems, in accordance with embodiments of the present disclosure;

FIG. 3 illustrates a flow chart of an example method for a handshake process between an information handling system and a chassis management controller, in accordance with embodiments of the present disclosure; and

FIG. 4 illustrates an example method for performing link optimization, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Preferred embodiments and their advantages are best understood by reference to FIGS. 1-4, wherein like numbers are used to indicate like and corresponding parts.

For the purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a personal digital assistant (PDA), a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (“CPU”) or hardware or software control logic. Additional components of the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various I/O devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components.

For the purposes of this disclosure, information handling resources may broadly refer to any component system, device or apparatus of an information handling system, including without limitation processors, buses, memories, I/O devices and/or interfaces, storage resources, network interfaces, motherboards, electro-mechanical devices (e.g., fans), displays, and power supplies.

For the purposes of this disclosure, computer-readable media may include any instrumentality or aggregation of instrumentalities that may retain data and/or instructions for a period of time. Computer-readable media may include, without limitation, storage media such as a direct access storage device (e.g., a hard disk drive or floppy disk), a sequential access storage device (e.g., a tape disk drive), compact disk, CD-ROM, DVD, random access memory (“RAM”), read-only memory (“ROM”), electrically erasable programmable read-only memory (“EEPROM”), and/or flash memory; as well as communications media such as wires, optical fibers, microwaves, radio waves, and other electromagnetic and/or optical carriers; and/or any combination of the foregoing.

Information handling systems often use an array of physical storage resources (e.g., disk drives), such as a Redundant Array of Independent Disks (“RAID”), for example, for storing information. Arrays of physical storage resources typically utilize multiple disks to perform input and output operations and can be structured to provide redundancy which may increase fault tolerance. Other advantages of arrays of physical storage resources may be increased data integrity, throughput and/or capacity. In operation, one or more physical storage resources disposed in an array of physical storage resources may appear to an operating system as a single logical storage unit or “logical unit.” Implementations of physical storage resource arrays can range from a few physical storage resources disposed in a chassis, to hundreds of physical storage resources disposed in one or more separate storage enclosures.

FIG. 1 illustrates a block diagram of an example system 100 having a chassis 101 with multiple information handling systems 102 and with various peripheral and I/O capabilities common to chassis 101 as a whole, in accordance with embodiments of the present disclosure. As depicted in FIG. 1, system 100 may comprise a chassis 101 including a plurality of information handling systems 102, a mid-plane 106, one or more switches 110, one or more chassis management controllers 112, a network interface 116, one or more slots 120, one or more cables 124, one or more storage interfaces 126, a disk drive backplane 128, a plurality of disk drives 130, an optical media drive 132, a keyboard-video-mouse (“KVM”) interface 134, and a user interface 136.

An information handling system 102 may generally be operable to receive data from and/or communicate data to one or more disk drives 130 and/or other information handling resources of chassis 101 via mid-plane 106 and/or switches 110. In certain embodiments, an information handling system 102 may be a server. In such embodiments, an information handling system may comprise a blade server having modular physical design. In these and other embodiments, an information handling system 102 may comprise an M class server. As depicted in FIG. 1, an information handling system 102 may include a processor 103, one or more switch interfaces 104 communicatively coupled to processor 103, a remote access controller (RAC) 105 communicatively coupled to processor 103, and a basic input/output system (BIOS) 107 communicatively coupled to processor 103.

A processor 103 may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation, a microprocessor, microcontroller, digital signal processor (“DSP”), application specific integrated circuit (“ASIC”), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, processor 103 may interpret and/or execute program instructions and/or process data stored in a memory, a disk drive 130, and/or another component of system 100.

A switch interface 104 may comprise any system, device, or apparatus configured to provide an interface between its associated information handling system 102 and switches 110. In some embodiments, switches 110 may comprise Peripheral Component Interconnect Express (“PCIe”) switches, in which case a switch interface 104 may comprise a switch card configured to create a PCIe-compliant interface between its associated information handling system 102 and switches 110. In other embodiments, a switch interface 104 may comprise an interposer. Use of switch interfaces 104 in information handling systems 102 may allow for minimal changes to be made to traditional servers (e.g., M class servers) while supporting the overall system architecture disclosed herein. Although FIG. 1 depicts an implementation including a single switch interface 104 per information handling system 102, in some embodiments each information handling system 102 may include a plurality of switch interfaces 104 for redundancy, high availability, and/or other reasons.

A RAC 105 may be implemented by, for example, a microprocessor, microcontroller, DSP, ASIC, EEPROM, or any combination thereof. RAC 105 may be configured to communicate with one or more of chassis management controllers 112 via midplane 106 (e.g., via an Ethernet management fabric). RAC 105 may be configured to provide out-of-band management facilities for management of information handling system 102. Such management may be made by elements of chassis 101 even if information handling system 102 is powered off or powered to a standby state. RAC 105 may include a processor, memory, and network connection separate from the rest of information handling system 102. In certain embodiments, RAC 105 may include or may be an integral part of a baseboard management controller (BMC), Dell Remote Access Controller (DRAC) or an Integrated Dell Remote Access Controller (iDRAC).

A BIOS 107 may include any system, device, or apparatus configured to identify, test, and/or initialize information handling resources of an information handling system 102, and/or initialize interoperation of information handling system 102 with other information handling resources of chassis 101. “BIOS” may broadly refer to any system, device, or apparatus configured to perform such functionality, including without limitation, a Unified Extensible Firmware Interface (UEFI). In some embodiments, BIOS 107 may be implemented as a program of instructions that may be read by and executed on processor 103 to carry out the functionality of BIOS 107. In these and other embodiments, BIOS 107 may comprise boot firmware configured to be the first code executed by processor 103 when information handling system 102 is booted and/or powered on. As part of its initialization functionality, code for BIOS 107 may be configured to set components of information handling system 102 into a known state, so that one or more applications (e.g., an operating system or other application programs) stored on compatible media (e.g., disk drives 130) may be executed by processor 103 and given control of information handling system 102.

Mid-plane 106 may comprise any system, device, or apparatus configured to interconnect modular information handling systems 102 with information handling resources. Accordingly, mid-plane 106 may include slots and/or connectors configured to receive information handling systems 102, switches 110, chassis management controllers 112, storage controllers 114, network interface 116, optical media drive 132, KVM interface 134, user interface 136, and/or other information handling resources. In one embodiment, mid-plane 106 may include a single board configured to interconnect modular information handling systems 102 with information handling resources. In another embodiment, mid-plane 106 may include multiple boards configured to interconnect modular information handling systems 102 with information handling resources. In yet another embodiment, mid-plane 106 may include cabling configured to interconnect modular information handling systems 102 with information handling resources.

A switch 110 may comprise any system, device, or apparatus configured to couple information handling systems 102 to storage controllers 114 (e.g., via mid-plane 106) and slots 120 and perform switching between information handling systems 102 and various information handling resources of system 100, including storage controllers 114 and slots 120. In certain embodiments, a switch 110 may comprise a PCIe switch. In other embodiments, a switch may comprise a generalized PC bus switch, an Infiniband switch, or other suitable switch. As shown in FIG. 1, chassis 101 may include a plurality of switches 110. In such embodiments, switches 110 may operate in a redundant mode for shared devices (e.g., storage controllers 114 and/or devices coupled to slots 120) and in non-redundant mode for non-shared/zoned devices. As used herein, shared devices may refer to those which may be visible to more than one information handling system 102, while non-shared devices may refer to those which are visible to only a single information handling system 102. In some embodiments, mid-plane 106 may include a single switch 110.

A chassis management controller 112 may be any system, device, or apparatus configured to facilitate management and/or control of system 100, its information handling systems 102, and/or one or more of its component information handling resources. A chassis management controller 112 may be configured to issue commands and/or other signals to manage and/or control information handling system 102 and/or information handling resources of system 100. A chassis management controller 112 may comprise a microprocessor, microcontroller, DSP, ASIC, field programmable gate array (“FPGA”), EEPROM, or any combination thereof. As shown in FIG. 1, a chassis management controller 112 may be coupled to mid-plane 106. Also as shown in FIG. 1, system 100 may include a plurality of chassis management controllers 112, and in such embodiments, chassis management controllers 112 may be configured as redundant. In some embodiments, a chassis management controller 112 may provide a user interface and high level controls for management of switches 110, including configuring assignments of individual information handling systems 102 to non-shared information handling resources of system 100. In these and other embodiments, a chassis management controller may define configurations of the storage subsystem (e.g., storage controllers 114, storage interfaces 126, disk drives 130, etc.) of system 100. For example, a chassis management controller may provide physical function configuration and status information that would normally occur at the driver level in traditional server implementations. Examples of physical functions include disk drive discovery and status, RAID configuration and logical volume mapping.

In addition or alternatively, a chassis management controller 112 may also provide a management console for user/administrator access to these functions. For example, a chassis management controller 112 may implement Web Services Management (“WS-MAN”) or another suitable management protocol permitting a user to remotely access a chassis management controller 112 to configure system 100 and its various information handling resources. In such embodiments, a chassis management controller 112 may interface with a network interface separate from network interface 116, thus allowing for “out-of-band” control of system 100, such that communications to and from chassis management controller 112 are communicated via a management channel physically isolated from an “in band” communication channel with network interface 116. Thus, for example, if a failure occurs in system 100 that prevents an administrator from interfacing with system 100 via network interface 116 and/or user interface 136 (e.g., operating system failure, power failure, etc.), the administrator may still be able to monitor and/or manage system 100 (e.g., to diagnose problems that may have caused failure) via a chassis management controller 112. In the same or alternative embodiments, chassis management controller 112 may allow an administrator to remotely manage one or more parameters associated with operation of system 100 and its various information handling resources (e.g., power usage, processor allocation, memory allocation, security privileges, etc.). Although FIG. 1 depicts chassis 101 as having two chassis management controllers 112, chassis 101 may include any suitable number of chassis management controllers 112.

A storage controller 114 may include any system, apparatus, or device operable to manage the communication of data between one or more of information handling systems 102 and one or more of disk drives 130. In certain embodiments, a storage controller 114 may provide functionality including, without limitation, disk aggregation and redundancy (e.g., RAID), I/O routing, and error detection and recovery. As shown in FIG. 1, a storage controller 114 may be coupled to a connector on a switch 110. Also as shown in FIG. 1, system 100 may include a plurality of storage controllers 114, and in such embodiments, storage controllers 114 may be configured as redundant. In addition or in the alternative, storage controllers 114 may in some embodiments be shared among two or more information handling systems 102. As also shown in FIG. 1, each storage controller 114 may be coupled to one or more storage interfaces 126 via cables 124. For example, in some embodiments, each storage controller 114 may be coupled to a single associated storage interface 126 via a cable 124. In other embodiments, each storage controller 114 may be coupled to two or more storage interfaces 126 via a plurality of cables 124, thus permitting redundancy as shown in FIG. 1. Storage controllers 114 may also have features supporting shared storage and high availability. For example, in PCIe implementations, a unique PCIe identifier may be used to indicate shared storage capability and compatibility in system 100.

As depicted in FIG. 1, switch 110 may have coupled thereto one or more slots 120. A slot 120 may include any system, device, or apparatus configured to allow addition of one or more expansion cards to chassis 101 in order to electrically couple such expansion cards to a switch 110. Such slots 120 may comprise any suitable combination of full-height risers, full-height slots, and low-profile slots. A full-height riser may include any system, device, or apparatus configured to allow addition of one or more expansion cards (e.g., a full-height slot) having a physical profile or form factor with dimensions that practically prevent such expansion cards to be coupled in a particular manner (e.g., perpendicularly) to mid-plane 106 and/or switch 110 (e.g., the proximity of information handling resources in chassis 101 prevents physical placement of an expansion card in such a manner). Accordingly, a full-height riser may itself physically couple with a low profile to mid-plane 106, a switch 110, or another component, and full-height cards may then be coupled to full-height slots of a full-height riser. On the other hand, low-profile slots may be configured to couple low-profile expansion cards to switches 110 without the need for a full-height riser.

Slots 120 may also include electrically conductive elements (e.g., edge connectors, traces, etc.) allowing for expansion cards inserted into slots 120 to be electrically coupled to switches 110. In operation, switches 110 may manage switching of communications between individual information handling systems 102 and expansion cards coupled to slots 120. In some embodiments, slots 120 may be nonshared (e.g., each slot 120 is associated with a single information handling system 102). In other embodiments, one or more of slots 120 may be shared among two or more information handling systems 102. In these and other embodiments, one or more slots 120 may be configured to be compatible with PCIe, generalized PC bus switch, Infiniband, or another suitable communication specification, standard, or protocol.

Network interface 116 may include any suitable system, apparatus, or device operable to serve as an interface between chassis 101 and an external network (e.g., a local area network or other network). Network interface 116 may enable information handling systems 102 to communicate with the external network using any suitable transmission protocol (e.g., TCP/IP) and/or standard (e.g., IEEE 802.11, Wi-Fi). In certain embodiments, network interface 116 may include a network interface card (“NIC”). In the same or alternative embodiments, network interface 116 may be configured to communicate via wireless transmissions. In the same or alternative embodiments, network interface 116 may provide physical access to a networking medium and/or provide a low-level addressing system (e.g., through the use of Media Access Control addresses). In some embodiments, network interface 116 may be implemented as a local area network (“LAN”) on motherboard (“LOM”) interface.

In some embodiments, various components of chassis 101 may be coupled to a planar. For example, a planar may interconnect switches 110, chassis management controller 112, storage controllers 114, network interface 116, optical media drive 132, KVM interface 134, user interface 136, and/or other modular information handling resources of chassis 101 to mid-plane 106 of system 100. Accordingly, such planar may include slots and/or connectors configured to interconnect with such information handling resources.

Storage interfaces 126 may include any system, device, or apparatus configured to facilitate communication between storage controllers 114 and disk drives 130. For example, a storage interface may serve to permit a relatively small number of communication links (e.g., two) between storage controllers 114 and storage interfaces 126 to communicate with a greater number (e.g., 25) of disk drives 130. Thus, a storage interface 126 may provide a switching mechanism and/or disk drive addressing mechanism that allows an information handling system 102 to communicate with numerous disk drives 130 via a limited number of communication links and/or channels. Accordingly, a storage interface 126 may operate like an Ethernet hub or network switch that allows multiple systems to be coupled using a single switch port (or relatively few switch ports). A storage interface 126 may be implemented as an expander (e.g., a Serial Attached SCSI (“SAS”) expander), an Ethernet switch, a FibreChannel switch, Internet Small Computer System Interface (iSCSI) switch, or any other suitable switch. In order to support high availability storage, system 100 may implement a plurality of redundant storage interfaces 126, as shown in FIG. 1.

Disk drive backplane 128 may comprise any system, device, or apparatus configured to interconnect modular storage interfaces 126 with modular disk drives 130. Accordingly, disk drive backplane 128 may include slots and/or connectors configured to receive storage interfaces 126 and/or disk drives 130. In some embodiments, system 100 may include two or more backplanes, in order to support differently-sized disk drive form factors. To support redundancy and high availability, a disk drive backplane 128 may be configured to receive a plurality (e.g., 2) of storage interfaces 126 which couple two storage controllers 114 to each disk drive 130.

Each disk drive 130 may include computer-readable media (e.g., magnetic storage media, optical storage media, opto-magnetic storage media, and/or other type of rotating storage media, flash memory, and/or other type of solid state storage media) and may be generally operable to store data and/or programs (e.g., one or more operating systems and/or one or more application programs). Although disk drives 130 are depicted as being internal to chassis 101 in FIG. 1, in some embodiments, one or more disk drives may be located external to chassis 101 (e.g., in one or more enclosures external to chassis 101).

Optical media drive 132 may be coupled to mid-plane 106 and may include any suitable system, apparatus, or device configured to read data from and/or write data to an optical storage medium (e.g., a compact disc, digital versatile disc, blue laser medium, and/or other optical medium). In certain embodiments, optical media drive 132 may use laser light or other electromagnetic energy to read and/or write data to an optical storage medium. In some embodiments, optical media drive 132 may be nonshared and may be user-configurable such that optical media drive 132 is associated with a single information handling system 102.

KVM interface 134 may be coupled to mid-plane 106 and may include any suitable system, apparatus, or device configured to couple to one or more of a keyboard, video display, and mouse and act as a switch between multiple information handling systems 102 and the keyboard, video display, and/or mouse, thus allowing a user to interface with a plurality of information handling systems 102 via a single keyboard, video display, and/or mouse.

User interface 136 may include any system, apparatus, or device via which a user may interact with system 100 and its various information handling resources by facilitating input from a user allowing the user to manipulate system 100 and output to a user allowing system 100 to indicate effects of the user's manipulation. For example, user interface 136 may include a display suitable for creating graphic images and/or alphanumeric characters recognizable to a user, and may include, for example, a liquid crystal display, cathode ray tube, a plasma screen, and/or a digital light processor projection monitor. In certain embodiments, such a display may be an integral part of chassis 101 and receive power from power supplies (not explicitly shown) of chassis 101, rather than being coupled to chassis 101 via a cable. In some embodiments, such display may comprise a touch screen device capable of receiving user input, wherein a touch sensor may be mechanically coupled or overlaid upon the display and may comprise any system, apparatus, or device suitable for detecting the presence and/or location of a tactile touch, including, for example, a resistive sensor, capacitive sensor, surface acoustic wave sensor, projected capacitance sensor, infrared sensor, strain gauge sensor, optical imaging sensor, dispersive signal technology sensor, and/or acoustic pulse recognition sensor. In these and other embodiments, user interface 136 may include other user interface elements (e.g., a keypad, buttons, and/or switches placed in proximity to a display) allowing a user to provide input to system 100. User interface 136 may be coupled to chassis management controllers 112 and/or other components of system 100, and thus may allow a user to configure various information handling resources of system 100 (e.g., assign individual information handling systems 102 to particular information handling resources).

When a system (e.g., system 100) is architected so as to allow information handling resources (e.g., PCIe adapters coupled to slots 120) to be located in a chassis having shared resources such that the information handling resources may be assigned to one information handling system or shared among a plurality of information handling resources, challenges may arise when needing to service an information handling resource.

Shared resources or devices, such as PCIe adapters coupled to slots 120, may be virtualized across multiple information handling systems 102. Non-shared resources or devices may be partitioned such that they are visible only to a single information handling system 102 at a time. Chassis management controller 112 may be configured to handle routing and switching through switches 110 to affect sharing of a resource to multiple information handling systems 102 or to affect dedicated assignment of a resource to a single information handling system 102.

FIG. 2 illustrates a more detailed block diagram of example system 100 configured for switches and devices in a multi-root I/O virtualization (“IOV”) environment for multiple information handling systems 102, in accordance with embodiments of the present disclosure.

As shown in FIG. 2, chassis 101 may include a management processor 248 communicatively coupled to one or more of chassis management controller 112 and switches 110. Management processor 248 may be any system, device, or apparatus configured to facilitate management and/or control of switches 110. Management processor 248 may be configured to issue commands and/or other signals to switches 110. Management processor 248 may comprise a microprocessor, microcontroller, DSP, ASIC, EEPROM, or any combination thereof. In one embodiment, management processor 248 may run a Linux operating system and include application-programming-interfaces (“APIs”) for supporting configuration of IOV in system 100 for sharing devices connected to slots 120 of chassis 101 to multiple information handling systems 102. The APIs of management processor 248 may provide the interface to chassis management controller 112 for configuring IOV. Management processor 248 may be configured to manage both switches 110. In one embodiment, management processor 248 may be communicatively coupled to an Ethernet management fabric 240 and to information handling systems 102. In another embodiment, chassis management controller 112 may be communicatively coupled to the information handling systems 102 through Ethernet management fabric 240. Chassis management controller 112 may be directly communicatively coupled to the Ethernet management fabric 240 or through, for example, management processor 248.

Although FIG. 2 depicts management controller 248 operable to facilitate management and/or control of switches 110, in some embodiments of the present disclosure, one or more chassis management controllers 112 may be configured to perform the functionality of management controller 248, in which a management controller 248 independent of the chassis management controllers 112 may not be present.

Chassis 101 may include multiple information handling systems 102. Chassis 101 may include any suitable number of information handling systems 102. In some embodiments, information handling systems 102 may be referred to as “blades”. Each information handling system 102 may include switch interfaces 104, a RAC 105, and a BIOS 107 as described in association with FIG. 1.

Switches 110 may contain PCIe cards instead of the typical blade Ethernet, Fibre Channel or InfiniBand cards. Switch interfaces 104 of the information handling systems 102 may couple to switches 110 through the switch interfaces 104 of switches 110. Switches 110 may couple information handling systems 102 to slots 120.

In one embodiment, each of information handling systems 102 may be communicatively coupled to each of switches 110 through one of switch interfaces 104 resident on the information handling system 102. For example, information handling system 102 a may be communicatively coupled to switch 110 a through switch interface 104 a and to switch 110 b through switch interface 104 b. Information handling system 102 b may be communicatively coupled to switch 110 a through switch interface 104 c and to switch 110 b through switch interface 104 d. Thus, each of switches 110 may provide its switching fabric to each of information handling systems 102 in order to route the given information handling system 102 to respective slots 120 associated with the switch 110.

Slots 120 may be configured to couple to associated devices 236, though fewer devices may be present than the associated capacity of chassis 101. Chassis 101 may include any suitable number of slots 120. In some embodiments, devices 236 may include PCIe-based cards or devices. Each such device 236 may represent an information handling resource to be selectively shared among multiple information handling systems 102 or dedicated to a single information handling system 102. A device 236 may comprise, for example, a RAID controller, network card, or other information handling resource. Furthermore, a device 236 may include a specific shared component such as a NIC. Devices 236 may include management information or circuitry configured to provide information to chassis 101 regarding the operation or specification of device 236. For example, a device 236 may include EEPROM 238 containing such information.

In order to support IOV, the driver and firmware of device 236 may include support for single root IOV (SR-IOV). To maintain routes between given information handling systems 102 and slots 120, switches 110 may include virtual hierarchies from slots 120 to information handling systems 102. Particular functions, such as virtual functions or shared functions, for SR-IOV for a given device 236 may be mapped in switch 110, providing behavior similar to multiple-root IOV (MR-IOV). Thus, in such case, a switch 110 may be considered a Multi-Root Aware (MRA) switch which bridges MR-IOV to SR-IOV so that SR-IOV virtual functions may be exposed to a mode as physical functions, such that an information handling system 102 is not aware that a given device 236 is shared. In one embodiment, wherein device 236 contains multiple information handling resources such as a NIC and USB interface, a function may be provided for each such information handling resource. Thus, from the perspective of information handling systems 102, such multiple information handling resources may appear to be separate and unrelated. A given slot 120 or device 236 which has been virtualized may be accessed by two or more virtual functions, which allows the sharing of the resource. Physical functions, as opposed to the above-described virtual functions or shared functions, may be mapped or stored in management processor 248. A physical function representing an information handling resource may be provided to a single information handling system 102. In cases where a device 236 contains multiple information handling resources, individual physical functions may be provided for each such resource. Multiple instances of a virtual function may be provided to multiple information handling systems 102. If, for example, multiple information handling systems 102 are sharing a device 236, then access to device 236 may be divided into multiple virtual NICs using virtual functions, each of which are mapped by switches 110 to the respective information handling system 102. Furthermore, specific APIs for accessing a given device 236 may be mapped or stored in management processor 248. Chassis management controller 112 may be configured to access these physical functions or APIs in management processor 248.

In some embodiments of system 100, many devices 236 of the same or similar functionality may be coupled to slots 120. In addition, such devices 236 may be shared among multiple information handling systems 102 or may be dedicated to a single information handling system 102. When a device 236 is shared among multiple information handling systems 102, and such device 236 becomes degraded (e.g., fails or becomes overused beyond its capacity), such degradation can result in loss of functionality of one or more of the information handling systems 102 associated with the device 236, all the while a device 236 with the same functionality may be sitting idle or well under capacity in another slot 120. Thus, a mechanism for dynamically allocating devices 236 to information handling systems 102 may be desirable.

Because information handling resources, such as those in devices 236 coupled to slots 120, are not located within an information handling system 102, but rather in a shared chassis using switches 110 to virtualize and route I/O communications among selected information handling systems 102, allocation of such information handling resources may not be directly controlled by an associated information handling system 102. Consequently, allocation of information handling resources such as devices 236 with information handling systems 102 in chassis 101 may be conducted by chassis management controller 112. As described in greater detail below, chassis management controller 112 may be configured to allocate or otherwise direct other components of chassis 101 to allocate devices 236 to information handling systems 102. It is noted that while the functionality described herein contemplates virtualization for shared devices 236, the functionality described herein may also be extended to nonshared devices as well.

As shown in FIG. 2, system chassis 101 may include internal switching fabrics (e.g., Fabric A and Fabric B). In the embodiments represented by FIG. 2, Fabric A is associated with switch 110 a (labeled “Switch 1”) and Fabric B is associated with switch 110 b (labeled “Switch 2”). Although not depicted in FIG. 2, storage controllers 114 may each be associated with a particular switching fabric of chassis 101 (e.g., based upon a slot or connectors via which a particular storage controller 114 is coupled to mid-plane 106).

Although the implementation of system chassis 101 with multiple information handling systems with various peripheral and I/O capabilities common to chassis 101 advantageously allows for high availability and redundant storage capabilities, multipath I/O settings must be configured in chassis 101, including configuring the various modular information handling systems 102 disposed in chassis 101. Such configuration may be complex and prone to error when manually performed by a user or administrator of chassis 101. Further complicating such configuration is that operating systems executing on individual modular information handling systems 102 must be configured to use particular information handling resources in order to effectively take advantage of multipath I/O.

In the systems depicted in FIGS. 1 and 2, a number of different communication links may be formed between an information handling system 102 and an associated device 236. In accordance with systems and methods herein disclosed, an information handling system 102 and a chassis management controller 112 may operate in concert to measure physical operational characteristics (e.g., link width, link speed) and based on such operational characteristics, determine whether to apply a remedial action (e.g., link tuning, link healing) to a particular link. Such remedial action may include modifying one or more link parameters (e.g., transmit coefficients, receive coefficients, transmit level, transmit pre-emphasis, transmit de-emphasis, receive attenuation factor, frequency-dependent boost factor, link termination, etc.).

In order to facilitate such link optimization, a handshake operation may take place between information handling system 102 and chassis management controller 112. In such handshake operation, during a boot process of an information handling system 102, BIOS 107 may issue a “Wait” indication to a RAC 105 and chassis management controller 112 and/or interrupt to the RAC 105 and chassis management controller 112. Each of RAC 105 and chassis management controller 112 may then perform optimization, and communicate respective “Release” notifications to BIOS 107 allowing BIOS 107 to continue with the boot process. An example of such a handshake operation is depicted in FIG. 3.

FIG. 3 illustrates a flow chart of an example method 300 for a handshake process between an information handling system 102 and a chassis management controller 112, in accordance with embodiments of the present disclosure. According to certain embodiments, method 300 may begin at step 302. As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system 100 as shown in FIGS. 1 and 2. As such, the preferred initialization point for method 300 and the order of the steps comprising method 300 may depend on the implementation chosen. In these and other embodiments, method 300 may be implemented as firmware, software, applications, functions, libraries, or other instructions.

At step 302, following a reset of an information handling system 102 (e.g., a powering on or boot occurring after insertion of information handling system 102 into chassis 101), BIOS 107 of such information handling system 102 may communicate a wait indicator to one or more information handling resources. For example, in some embodiments, communication of such wait indicator may comprise setting an appropriate variable in a computer-readable medium (e.g., a complex programmable logic device of information handling system 102) accessible to BIOS 107. Such computer-readable medium may also be accessible to RAC 105 of the information handling system 102, such that RAC 105 may retrieve such wait indicator. After communicating the wait indicator, BIOS 107 may poll for receipt of a release indicator from RAC 105 and chassis management controller 112.

At step 304, information handling system 102 may communicate the wait indicator to a chassis management controller 112. For example, information handling system 102 may communicate the wait indicator from a computer-readable medium (e.g., a complex programmable logic device) of information handling system 102 to chassis management controller 112 via one or more serial buses.

At step 306 a, in response to receipt of the wait indicator, chassis management controller 112 may perform link optimization operations on switches 110 and/or devices 236 coupled to slots 120. An example of such link optimization operations is described in greater detail below in reference to FIG. 4.

At step 308 a, once link optimization operations of chassis management controller 112 are complete, chassis management controller 112 may communicate a release indicator to information handling system 102. In some embodiments, chassis management controller 112 may communicate the release indicator to a computer-readable medium (e.g., a complex programmable logic device) of information handling system 102 to chassis management controller 112 via one or more serial buses.

At step 306 b, in response to communication of the wait indicator by BIOS 107, RAC 105 may perform link optimization operations on switch interface 104. An example of such link optimization operations is described in greater detail below in reference to FIG. 4. In some embodiments, in lieu of RAC 105 performing link optimization operations, such link optimization operations may be performed by BIOS 106, in which case the handshake mechanism of FIG. 3 may not occur between BIOS 107 and RAC 105.

At step 308 b, once link optimization operations of RAC 105 are complete, RAC 105 may communicate a release indicator. In some embodiments, communication of the release indicator may set an appropriate variable in a computer-readable medium (e.g., a complex programmable logic device of information handling system 102) accessible to BIOS 107 and RAC 105.

In some embodiments, the steps 306 a and 308 a may be performed substantially contemporaneously with steps 306 b and 308 b.

At step 310, in response to release indicators being communicated from each of RAC 105 and chassis management controller 112 (or, in some embodiments, in response to expiration of a timeout for receipt of the release indicators), BIOS 107 may continue booting of information handling system 102. In the case where a timeout expires prior to receipt of release indicators, BIOS 107 may issue an alert (e.g., via a user interface coupled to information handling system 102) and/or may pause BIOS execution until user acknowledgement of the alert.

Although FIG. 3 discloses a particular number of steps to be taken with respect to method 300, method 300 may be executed with greater or fewer steps than those depicted in FIG. 3. In addition, although FIG. 3 discloses a certain order of steps to be taken with respect to method 300, the steps comprising method 300 may be completed in any suitable order.

Method 300 may be implemented using system 100, components thereof or any other system such as those shown in FIGS. 1 and 2 operable to implement method 300. In certain embodiments, method 300 may be implemented partially or fully in software and/or firmware embodied in computer-readable media.

Various types of link optimization may occur at the time of switch initialization, and some types of link optimization require some or all of BIOS-initiated resets of information handling system 102 to have occurred but also require switch enumeration and operating system boot to have occurred. Accordingly, the handshake mechanism of FIG. 3 may pause BIOS 107 execution at a point in time suitable for link optimization, and then once link optimization is complete, allow the boot process of BIOS 107 to continue.

FIG. 4 illustrates an example method 400 for performing link optimization, in accordance with embodiments of the present disclosure. According to certain embodiments, method 400 may begin at step 402. As noted above, teachings of the present disclosure may be implemented in a variety of configurations of system 100 as shown in FIGS. 1 and 2. As such, the preferred initialization point for method 400 and the order of the steps comprising method 400 may depend on the implementation chosen. In these and other embodiments, method 300 may be implemented as firmware, software, applications, functions, libraries, or other instructions.

At step 402, in response to communication of the wait indication by BIOS 107, a management controller (e.g., RAC 105 and/or chassis management controller 112) may determine if a device 236 is on a device whitelist. Such device whitelist may be stored on computer-readable media accessible to the management controller, and may include a list of devices known to operate at less than their target speeds and/or link widths. In some embodiments, such whitelist may also set forth, for each device, such device's typical speed and/or link width. If a device 236 is on the device whitelist, method 400 may proceed to step 404. Otherwise, method 400 may proceed to step 406.

At step 404, responsive to a determination that device 236 appears on the whitelist, the management controller may retrieve the typical speed and/or link width of the device from the whitelist. Method 400 may then proceed to step 408.

At step 406, responsive to a determination that device 236 is absent from the whitelist, the management controller may retrieve the target speed and/or link width of the device from a configuration space for the link including device 236. Such configuration space may reside in link status and/or control registers of a device 236 and may include current, target, and/or maximum link speed and link width. The management controller may receive such via a sideband interface of a switch 110 including the link (e.g., an interface of the switch 110 other than the interface used to communicate data over the link) and/or may retrieve such information from a device 236 either via a sideband interface of the device 236 (e.g., an interface of the device 236 other than the interface used to communicate data over the link, such as a System Management Bus sideband interface or an Inter-Integrated Circuit interface) or in-band via the communication bus (e.g., PCIe bus) for the link by assigning device 236 to a virtual switch of switch 110 which allows a management controller with a root complex (e.g., a PCIe root complex) to read such information in-band through the bus.

At step 408, based on the retrieved target or typical speed and/or link width for a device, the management controller may determine if the actual speed and/or link width is below that of the target or typical speed and/or link width. If the actual speed and/or link width is below that of the target or typical speed and/or link width, method 400 may proceed to step 410. If the actual speed and/or link width is equal to that of the target or typical speed and/or link width, method 400 may proceed to step 412.

At step 410, in response to determining that the actual speed and/or link width is below that of the target or typical speed and/or link width, the management controller may perform remedial action (e.g., tuning and/or healing) to the link in order to increase the actual speed and/or link width to match that typical or target speed and/or link width, as appropriate. The management controller may log information regarding such remedial action, including whether an actual speed and/or link width remains below that of the typical or target speed and/or link width.

At step 412, the management controller may communicate the release indication, indicating that link optimization is complete. After completion of step 412, method 400 may end.

Although FIG. 4 discloses a particular number of steps to be taken with respect to method 400, method 400 may be executed with greater or fewer steps than those depicted in FIG. 4. In addition, although FIG. 4 discloses a certain order of steps to be taken with respect to method 400, the steps comprising method 400 may be completed in any suitable order.

Method 400 may be implemented using system 100, components thereof or any other system such as those shown in FIGS. 1 and 2 operable to implement method 400. In certain embodiments, method 400 may be implemented partially or fully in software and/or firmware embodied in computer-readable media.

Although the foregoing contemplates link tuning and healing operations occurring during boot of an information handling system, in some embodiments, chassis management controller 112 may perform such link tuning and healing iteratively during runtime. For example, chassis management controller 112 may use steps similar or identical to steps 402-410 to perform tuning.

To illustrate, upon detecting a transmission error count or error rate that exceeds a threshold, chassis management controller 112 may attempt to improve the link reliability by retuning transmit and receive equalization parameters. Changes in the operating environment—such as temperature—may affect the error rate in which case such retuning may yield more reliable operation. Any number of methods for iterative tuning may be employed. One example is to apply an annealing process. Iterating through each tunable parameter, chassis management controller 112 may adjust a parameter higher and then lower. If either new setting yields an improved error rate or other observable improvement, chassis management controller 112 may preserve the new parameter value and the process may iterate to the next tunable parameter. Otherwise, the parameter value is returned to its original value and the next tunable parameter may be adjusted in a similar manner.

As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements.

This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.

All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure. 

What is claimed is:
 1. An article of manufacture comprising: a non-transitory computer readable medium; and computer-executable instructions carried on the computer readable medium, the instructions readable by a processor, the instructions, when read and executed, for causing the processor to, during boot of a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources: pause execution of a basic input/output system; communicate a first indicator, wherein the first indicator causes a chassis management controller of the chassis to perform link optimization operations of a communication link between the modular information handling system and a modular information handling resource; and in response to communication by the chassis management controller of a second indicator, the second indicator indicating completion of link optimization operations by the chassis management controller, unpause execution of the basic input/output system.
 2. The article of claim 1, wherein the communication link comprises a Peripheral Component Interconnect Express link.
 3. The article of claim 1, wherein: the first indicator causes a management controller of the modular information handling system to perform link optimization operations of the communication link; and in response to communication by the chassis management controller of the second indicator and communication by the management controller of a third indicator, the third indicator indicating completion of link optimization operations by the management controller, unpause execution of the basic input/output system.
 4. The article of claim 3, wherein the management controller comprises a baseboard management controller.
 5. The article of claim 3, wherein the management controller comprises a remote access controller.
 6. The article of claim 1, wherein pausing the basic input/output system comprises pausing operations of the basic input/output system other than performance by the basic input/output system link optimization operations of the communication link.
 7. A method comprising, during boot of a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources: pausing execution of a basic input/output system; communicating a first indicator, wherein the first indicator causes a chassis management controller of the chassis to perform link optimization operations of a communication link between the modular information handling system and a modular information handling resource; and in response to communication by the chassis management controller of a second indicator, the second indicator indicating completion of link optimization operations by the chassis management controller, unpausing execution of the basic input/output system.
 8. The method of claim 7, wherein the communication link comprises a Peripheral Component Interconnect Express link.
 9. The method of claim 7, wherein: the first indicator causes a management controller of the modular information handling system to perform link optimization operations of the communication link; and in response to communication by the chassis management controller of the second indicator and communication by the management controller of a third indicator, the third indicator indicating completion of link optimization operations by the management controller, unpausing execution of the basic input/output system.
 10. The method of claim 9, wherein the management controller comprises a baseboard management controller.
 11. The method of claim 9, wherein the management controller comprises a remote access controller.
 12. The method of claim 7, wherein pausing the basic input/output system comprises pausing operations of the basic input/output system other than performance by the basic input/output system link optimization operations of the communication link.
 13. An article of manufacture comprising: a non-transitory computer readable medium; and computer-executable instructions carried on the computer readable medium, the instructions readable by a processor, the instructions, when read and executed, for causing the processor to perform link optimization operations in a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources, the link optimization operations comprising: determining if a modular information handling resource disposed in the chassis and communicatively coupled to a modular information handling system disposed in the chassis is identified in a whitelist; if the modular information handling resource is identified in the whitelist, retrieving typical operating parameters associated with the information handling resource; if the modular information handling resource is identified in the whitelist, retrieving target operating parameters associated with the information handling resource; determining if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system satisfy the typical operating parameters or the target operating parameters; and performing a remedial action if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system do not satisfy the typical operating parameters or the target operating parameters.
 14. The article of claim 13, wherein the typical operating parameters, the target operating parameters, and the actual operating parameters comprise at least one of a speed of the communication link and a link width of the communication link.
 15. The article of claim 13, wherein the remedial action comprises at least one of tuning the communication link such that the actual operating parameters satisfy the typical operating parameters or the target operating parameters and healing the communication link.
 16. The article of claim 13, the instructions for causing the processor to perform the link optimization operations during a boot of the modular information handling system.
 17. A method comprising, performing link optimization operations in a modular information handling system disposed in a chassis configured to receive a plurality of modular information handling systems and a plurality of modular information handling resources, the link optimization operations comprising: determining if a modular information handling resource disposed in the chassis and communicatively coupled to a modular information handling system disposed in the chassis is identified in a whitelist; if the modular information handling resource is identified in the whitelist, retrieving typical operating parameters associated with the information handling resource; if the modular information handling resource is identified in the whitelist, retrieving target operating parameters associated with the information handling resource; determining if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system satisfy the typical operating parameters or the target operating parameters; and performing a remedial action if actual operating parameters of a communication link between the modular information handling resource and the modular information handling system do not satisfy the typical operating parameters or the target operating parameters.
 18. The method of claim 17, wherein the typical operating parameters, the target operating parameters, and the actual operating parameters comprise at least one of a speed of the communication link and a link width of the communication link.
 19. The method of claim 17, wherein the remedial action comprises at least one of tuning the communication link such that the actual operating parameters satisfy the typical operating parameters or the target operating parameters and healing the communication link.
 20. The method of claim 17, further comprising performing the link optimization operations during a boot of the modular information handling system. 